Probing Parton Orbital Angular Momentum in Longitudinally Polarized Nucleon

Abstract

While the total orbital angular momentum (OAM) of a definite quark flavor in a longitudinally-polarized nucleon can be obtained through a sum rule involving twist-two generalized parton distribution (GPDs), its distribution as a function of parton momentum in light-front coordinates is more complicated to define and measure because it involves intrinsically twist-three effects. In this paper, we consider two different parton OAM distributions. The first is manifestly gauge invariant, and its moments are local operators and calculable in lattice QCD. We show that it can potentially be measured through twist-three GPDs. The second is the much-debated canonical OAM distribution natural in free-field theory and light-cone gauge. We show the latter in light-cone gauge can also be related to twist-three GPDs as well as quantum phase-space Wigner distributions, both being measurable in high-energy experiments.

14 pages, no figure

References in corpus (10)

• Universality of Unintegrated Gluon Distributions at small x
• Global Analysis of Helicity Parton Densities and Their Uncertainties
• Quark Wigner Distributions and Orbital Angular Momentum
• kt-factorization for Hard Processes in Nuclei
• Twist-3 Formalism for Single Transverse Spin Asymmetry Reexamined: Semi-Inclusive Deep Inelastic Scattering
• Single Transverse Spin Asymmetry for Large-p_T Pion Production in Semi-Inclusive Deep Inelastic Scattering
• Parton Orbital Angular Momentum and Final State Interactions
• Transverse Polarization of the Nucleon in Parton Picture
• Twist-three relations of gluonic correlators for the transversely polarized nucleon
• Gluon Spin, Canonical Momentum, and Gauge Symmetry

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